Emergency vehicles such as police cars, fire response vehicles, ambulances, and the like require highly visible warning lights and signals to alert motorists of their presence. Warning lights visible to motorists from a reasonable distance allow drivers to safely make way for an overtaking emergency vehicle. Many emergency vehicles have large glass windshields and/or rear windows. These surfaces offer ideal locations for emergency signals. Unfortunately, these advantageous surfaces have heretofore not been unutilized for such purposes because any warning signal device placed therein has significantly limited visibility of the driver of the emergency vehicle. It would be advantageous, therefore, to have an emergency signaling system which could take advantage of highly visible placement positions such as a rear window or windshield of an emergency vehicle without significantly affecting the vehicle driver's visibility.